12 WATER CYCLE Water on our planet moves in a continuous cycle.water evaporates, heat is absorbed to form water vaporvapors rise, cool and condense into clouds.water droplets become heavy enough to fall -precipitation.water fills lakes, streams and rivers, and eventually flows back into the oceans where evaporation starts the process anew.transpiration by plant leaves: as plants absorb water from the soil, the water moves from the roots through the stems to the leaves, where it can evaporate.

15 Measurement of Water VaporHumidity - the amount of water vapor in the airTemperature affects how much moisture is in the airWarmer air can hold MORE moisture – molecules are farther apart creating more space for the water molecules to fit inDew point – The temperature at which water vapor will condenseRelative Humidity – the amount of water vapor present compared to the amount that could be held at a specific temperature

16 AIR PRESSURE Weight of air columnWarmer air is LESS DENSE – low pressureCooler air is MORE DENSE – high pressure

18 CLOUDS – How do they form?Air risesCools to its dew point through expansion (Less pressure, molecules spread out, heat is given off)Water vapor molecules "clump together" faster than they are torn apart by their thermal energy.Some of that (invisible) water vapor condenses to form (visible) cloud droplets or ice crystals.

20 cloud particles become too heavy to remain suspended in the airPRECIPITATIONRainliquid precipitationHailIce precipitationFreezing rainsuper cooled droplets freezing on impactSleetFrozen raindrops that bounce on impact with the groundSnowan aggregate of ice crystalscloud particles become too heavy to remain suspended in the air

21 Air moving from one temperature or pressure area to anotherWIND - GlobalAir moving from one temperature or pressure area to anotherAffected by Coriolis Effectapparent deflection of air to the right in the Northern hemisphere, to the left in the southern hemispherecaused by Earth’s rotation

27 JET STREAMBands of strong winds near the top of the troposphere at the northern and southern boundaries of the prevailing westerlies

28 Ocean Currents RELATEDMovement of both the air and the oceans is controlled by temperature differencesThe result is a transfer of heat from the equator to the poles. About half the heat transport around the planet is by the oceans, making oceans an extremely important part of the Earth's climate control system. If ocean circulation is changed by global warming, major changes in climate are therefore likely.

30 Greenhouse EffectThe warming effect of the Earth’s atmosphere is called the greenhouse effect.Gases in the atmosphere that trap solar energy are called greenhouse gasesWater vaporCarbon dioxideMethaneHuman Activities that ADD greenhouse gases:carbon dioxide (produced for example, by the burning of fossil fuels)nitrogen oxides (from car exhausts)Result – could be GOBAL WARMING

31 Possible effects of the global warmingPositiveFarmers in cooler regions could plant two crops a yearNegativeHigher temperature leads to water evaporating more quickly from soil – leading to “dust bowl” conditionsRise in ocean temperatures could spawn more hurricanesRise in water temperatures would cause the water to expand, raising sea levels around the worldGlaciers and polar ice caps might partially meltCFCs (from aerosols and refrigerators)

32 What is Ozone?Ozone is made of three oxygen atoms (O3). The oxygen we find in our atmosphere is made up of two oxygen atoms (O2). Because of its chemical formulation, a single atom of oxygen (O) is unstable. That is, it wants to combine with something else. That is why oxygen is almost always found in pairs, in its O2 (diatomic) form, where it is more stable. Ozone is less stable than O2, because it wants to return to the diatomic state by giving up an oxygen atomOzone is unstable and will readily combine with other atoms.Ozone is found in the stratosphere, where it blocks the sun's ultraviolet (UV) waves and prevents them from reaching the earth's surface.Ozone is also found in the troposphere, where it can damage living tissue and human-produced objects. It is generated both from certain types of pollution and natural sources.Ozone is constantly being formed in the earth's atmosphere by the action of the sun's ultraviolet radiation on oxygen molecules. Ultraviolet light splits the molecules apart by breaking the bonds between the atoms. A highly reactive free oxygen atom then collides with another oxygen molecule to form an ozone molecule. Because ozone is unstable, ultraviolet light quickly breaks it up, and the process begins again.

35 SMOG Photochemical Smog Caused by the action of sunlight on chemicalsNitrogen oxides – Nitrogen Oxide (NO) produced from burning fossil fuels reacts with oxygen in the atmosphere to make Nitrogen Dioxide (NO2)Hydrocarbons – organics given off by some plants, from fuels evaporating and incomplete burning of fuelThese along with others react with each other in the presence of sunlight to form a mix of ozone and other chemicalsSMOG

37 ACID RAIN – What is it?Sulfur dioxide (SO2) and nitrogen oxides (NOX) released into the air from burning fossil fuels.Combined with water and other chemicals, sulfur and nitrogen oxides become sulfuric and nitric acid.These acids may travel long distances before falling to the earth as rain, snow, sleet, hail, fog, dew or dust.

38 ACID RAIN – How do you know?Acid rain is measured using the pH scale.The pH scale ranges from 0 (very acidic) to 14 (most alkaline). Seven is neutral.Rain is by nature slightly acidic, with a pH of 5.6. Any precipitation below that is considered "acid rain".Because the scale is logarithmic, a pH of 4.6 is ten times more acidic than normal rainwater and a pH of 3.6 is a hundred times more acidic.The average pH of rain in Vermont is between 4.2 and 4.4 with extremes ranging from 2.4 to 7.4.

41 ACID RAIN – Solutions?SCRUBBERS - filters in smokestacks of factories and power plants to remove pollutants Very expensive to install.USE ALTERNATIVE ENERGY PRODUCTION METHODS – Wind or solar power not harmful to the environment. However, the cost of replacing all of the fossil fuel power stations with either wind farms or solar power is prohibitive and almost impossible. It would take 600 wind turbines to produce the same electricity as one coal-fired power station.USE LESS ENERGY – insulate houses better, lower ceilings, use the car less, walk more, bicycle, public transportationCATALYTIC CONVERTERS - catalytic converters on car exhausts remove around 90% of the pollutants released during the combustion process.